## Astronomers Discover Largest Structure In the Universe 143 143

KentuckyFC writes

*"Until now, the largest known structure in the Universe was the Huge-LQG (Large Quasar Group), a cluster of 73 quasars stretching over a distance of 4 billion light years. Now astronomers say they've spotted something even bigger in data from gamma ray bursts, the final explosions of energy released by stars as they die and the universe's most energetic events. Astronomers have measured the distance to 283 of these bursts and mapped their position in the universe. This throws up a surprise. At a distance of ten billion light years, there are more gamma ray bursts than expected if they were evenly distributed throughout the universe. This implies the existence of a structure at this distance that is about ten billion light years across and so dwarfs the Huge-LQG. What's odd about the discovery is that the Cosmological principle--one of the fundamental tenets of cosmology--holds that the distribution of matter in the universe will appear uniform if viewed at a large enough scale. And yet, structures clearly emerge at every scale astronomers can see. The new discovery doesn't disprove the principle but it does provide some interesting food for thought for theorists."*
## Re:Random distribution (Score:5, Interesting)

Thank God we have people on Slashdot to tell us things like this. Where would we have been if generations of cosmologists were entirely ignorant of statistics or gravitational physics? The mind boggles!

Sorry, but the problem isn't that there are lumps - if there weren't our existence would be a bit suspect since we live on the edge of a reasonably large lump (the Virgo supercluster) ourselves. The problem (if you want to call it a problem; it's more an interesting question) concerns the *size* of the lumps. We can predict with reasonable certainty the probability of a bound structure of such and such a size appearing in the universe. That's quite straightforward in principle. And structures this big are pushing the bounds of the standard cosmological model quite hard; basically, they shouldn't really be there. I don't know the actual probability but it's extremely low, and low enough that we would not expect to see it. That there are now three structures that are rather too large (this one, if it comes to be accepted as a genuine structure; the Sloan great wall, if it turns out to actually be a structure; and the CfA great wall) is getting interesting.

## Re:Enter Metaphysics (Score:2, Interesting)

By forming new ones, I presume you mean taking a collection of some random radio emissions scattered around the universe and arbitrarily deciding they are a "structure"?

## Re:quasardilla supreme (Score:3, Interesting)

## Re:Enter Metaphysics (Score:4, Interesting)

Even a trivially simplified case (say I have a coin, that I allege is fair, and you get to flip it as many times as you want before deciding if you believe me) cannot be decided with certainty. Any finite sequence of flips is equally likely as any other (though sequences that are approximately 50/50 should be overwhelmingly more common if the coin is in fact fair, I have no idea how the behavior changes if you choose infinitely many flips), and you can only gain greater or lesser doubt in the fairness of my coin.

For a much more complex phenomenon, like the origin of the universe, deciding whether you are simply looking at an improbable; but perfectly possible, local perturbation, or whether there is some 'tilt' in the system not covered by current accounts... It's a mathematically cogent exercise; but 'mathematically cogent' and 'easy' are very, very, very different things.